Polyol-containing carriers and solvents are well known for use in topical antiperspirant compositions. These carriers are most typically used to solubilize the antiperspirant active or as coupling agents during the manufacturing process. These polyol carriers are typically aliphatic polyhydric alcohols which have from 2 to 12 carbon atoms, examples of which include ethylene glycol, diethylene glycol, butylene glycol (1,3-butane-diol), 1,2-proplyene glycol, 1,3-propylene glycol, glycerine (1,2,3-trihydroxy propane), 2-methyl-2,4-pentane-diol (hexylene glycol), 2-ethyl-1,3-hexane-diol, 1,2,6-hexanetriol, 1,2,4-butanetriol, and combinations thereof.
Polyol-containing carriers are especially useful in formulating clear or translucent antiperspirant compositions. These compositions are typically anhydrous systems containing solubilized antiperspirant active, wherein the polyol carrier is used to help solubilize the active and in most cases provides the primary carrier material within which the solubilized active is miscible or dispersed within.
Many polyol-containing carriers, however, can cause skin irritation when topically applied to the underarms or other sensitive areas of the skin. This skin irritation is especially problematic when the applied composition is an anhydrous system containing higher concentrations of the polyol carrier. These higher polyol concentrations are often necessary in anhydrous antiperspirant compositions to successfully couple product gellants, structurants, thickening agents or other similar materials with other product carriers or solvents. This skin irritation, especially when caused by higher polyol concentrations, is especially problematic in a small percentage of the population that is unusually sensitive to topical polyol irritation. Although this type skin of irritation can be minimized by adding lower irritation solvents such as mineral oil or volatile silicones, these low irritation solvents are not miscible with higher concentrations of short carbon chain, highly polar, polyol solvents, e.g., dipropylene glycol, glycerin.
One recent attempt at providing improved polyol-containing carriers for use in antiperspirant products is described in U.S. patent application Ser. No. 09/071,178 (Swaile et al.) filed Jul. 27, 1999. The Swaile et al. Application discloses antiperspirant compositions containing 1,2-hexanediol, and the use of such compositions to provide improved mildness, cosmetics and antiperspirant efficacy.
It has now been found that polyol-containing carriers other than 1,2-hexanediol can also be selected for use in antiperspirant compositions which provide improved mildness, cosmetics and antiperspirant efficacy, provided that the selection is limited to those liquid polyols having at least 2 hydroxyl groups and preferably having at least 4 adjacent carbon atoms, wherein 2 of the hydroxyl groups are attached to the .alpha. and .beta. carbons of the liquid polyol and no more than 4 hydroxyl groups are attached to adjacent carbon atoms, and wherein the liquid polyol has a ClogP value of less than about 2.0 and the mole ratio of the liquid polyol to the aluminum and zirconium is at least about 2.0:1.
It has also been found that the antiperspirant efficacy of these antiperspirant compositions can be improved by the addition of a water-soluble, neutral amino acid and chlorine-containing inorganic acid, provided that within the composition the mole ratio of the neutral amino acid to the zirconium and aluminum is from about 0.09 to about 0.24, the mole ratio of the liquid polyol to the aluminum and zirconium is at least about 2.0:1, and the mole ratio of the zirconium and aluminum to chlorine is less than about 1.30:1.
Although acid activated antiperspirant actives are known in the antiperspirant art, e.g., U.S. Pat. No. 4,331,609 (Orr), the art teaches that such acid-enhanced actives can be formulated as spray dried solids or solubilized in an aqueous medium, but it fails to teach formulation as an anhydrous composition containing solubilized acid enhanced active. It has now been found that these acid enhanced actives can be formulated as solubilized active in the anhydrous composition of the present invention. Using acid activated actives in these compositions improves manufacturing efficiency by relying upon acid activation rather than heat activation of the antiperspirant active. Heat activation processes are typically more expensive and require more manufacturing steps than acid activation processes.